The present disclosure generally relates to oil and gas operations and, more particularly, the selection of optimal hydrate inhibitor surfactants for use during oil and gas operations.
The production of underground hydrocarbons often requires substantial investment in drilling and pumping equipment. When production is underway, up-front costs can be recouped provided that operating costs remain low enough for the sale of oil and/or gas to be profitable. Additionally, midstream and downstream processing costs of produced hydrocarbons (i.e., oil and natural gas, which may collectively be referred to herein simply as “oil”) may affect the profitability of the produced hydrocarbons. Gas hydrate production in cold climates, in deepwater environments, or at any point during hydrocarbon production may interfere with this profitability.
Gas hydrates are a form of a unique class of chemical compounds known as clathrates. They are characterized by a rigid, open network of bonded host molecules that enclose, without direct chemical bonding, appropriately sized guest molecules of another substance. For example, in the case of gas hydrates a crystalline water molecule acts as the host molecule, which forms a “cage” around a smaller hydrocarbon molecule (e.g., methane), thereby yielding ice-like crystals of gas and water. These gas hydrates tend to adhere to each other, resulting in large ice-like crystals formed on the surface of hydrocarbon conduits that act as blockades (“gas hydrate plugs”). Accordingly, during production, storage, and transportation (e.g., pipelines) of hydrocarbons, the formation of gas hydrates may interfere with hydrocarbon production flow, which can block tubings, flow lines, pipelines, and other conduits (e.g., drill strings) through which produced hydrocarbons are intended to flow.
Various methods have been employed for inhibiting gas hydrate formation. For example, the traditional approach to gas hydrate inhibition and/or dissolution after formation involves the addition of sufficient quantities of a gas hydrate inhibitor surfactants (e.g., a thermodynamic gas hydrate inhibitor surfactants) to a production system (e.g., downhole, in a pipeline, and the like). Although the term “gas hydrate inhibitor surfactant” is used herein, such substances are also known as anti-agglomerates, and will be understood to be interchangeable. Determining the optimal type and concentration, or mixtures thereof of gas hydrate inhibitor surfactants is typically determined using rocking cell apparatus methodologies, which are performed in laboratory settings. In some instances, the rocking cell apparatus methodologies may be time consuming and may limit analysis to only single gas hydrate types at a time.